Mobile excavation machines, such as, for example, dozers, agricultural tractors, and scrapers, often include one or more material engaging implements utilized to cultivate, dig, rip or otherwise disturb a ground surface. The ground surface can include non-homogenous loose soil or compacted material that can be easy or difficult for the machine to process. As the machines traverse a site that has changing terrain and/or varying ground surface conditions, the magnitude of resistance applied to the implements by the material also varies, and higher amounts of resistance can lead to machine slip. Generally, slip represents the error between driven speed and actual machine travel speed. In order to ensure that a maximum productivity of the machine is attained without damaging the machine (i.e. a maximum amount of power is transmitted to the material with minimal slip), the operator of the machine must continuously alter settings of the machine and implements to accommodate the changing terrain and ground surface conditions. This continuous altering can be tiring for even a skilled operator and difficult, if not impossible, for a novice operator to achieve optimally.
One way to efficiently accommodate changes in terrain and surface composition may include autonomously controlling the machine during portions of the excavation process. One such autonomously controlled machine is described in U.S. Pat. No. 4,062,539 (“the '539 patent”) issued to Tetsuka et al. on Dec. 13, 1977. The '539 patent discloses a control system provided with a ripper detector, which detects when a ripping tool is operated in a piercing mode or a digging mode. In the piercing mode, the angle of a ripping tool's shank is automatically adjusted to a preset piercing angle, while in the digging mode, the shank angle is adjusted to a preset digging angle. Limit switches for detecting upper and lower limit positions of the ripping tool's shank are provided for automatically raising and lowering the tool between these limits, while adjusting the shank angle. Further, an overload detector is provided for automatically raising the shank when its load exceeds a predetermined load, and lowering the shank when the load decreases below it.
Although the control system of the '539 patent may improve machine efficiency and reduce operator fatigue by automating some of the functions normally controlled by the operator, it may be limited. Specifically, the control system may consider too few inputs when raising and lowering the shank. That is, because the control system only considers load, as measured at the shank, there may be situations when the load on the shank is below the predetermined load and, yet, the shank penetration is too deep for maximum productivity such as when the machine is on a loose or viscous surface and slipping. In addition, because the control system only controls shank operation, the operator may still be required to expend time and energy controlling machine functions such as speed and acceleration. Further, the control system may be applicable to only a single ripper configuration.
The present disclosure is directed to overcoming one or more of the shortcomings set forth above.